What a conditional use permit to add 12 RV sites actually involves

A public hearing does not mean neighbors get a veto. It means they get to speak and the board has to consider it. In practice a loud room can push a board toward conditions, buffer plantings, a lighting spec, a limit on hours at a shared amenity, and those conditions carry costs that should be assumed going in.

Sequence the septic ahead of the land use work, because it can kill the project outright and it is cheaper to learn that first.

Most states regulate onsite wastewater by design flow, and RV sites are assigned a gallons per day figure per site in the state code. Twelve full hookup sites at whatever your state assigns, commonly in the range of 50 to 100 gallons per day per site, is a defined load added to your existing system. If your current field was sized for 30 sites you will likely need either a field expansion or a new field, which requires soil evaluation and percolation testing on that 2.4 acres. Those tests are seasonal in many states because they want the water table at its high point. Missing that window is how a project loses a year. The specific design flow figures and testing requirements vary by state, so get them from your state or county health department in writing.

On your numbers, 170k for 12 sites at 14k each does not include the wastewater capacity, engineering, permit fees, or whatever conditions come out of the hearing. Wastewater alone can run from modest to more than the rest of the project combined if you need an engineered system.

Your 55k of revenue against a real cost that might land at 250k is still a reasonable return if it comes in, so the question is how much you spend to find out. Soil testing and a pre application meeting with planning and health together will cost a few thousand and answer most of it. Do that before you spend anything on stamped drawings.

Following this closely because I did not know a park could be nonconforming and still be fine. That reframes a couple of listings I had written off.

The other thing worth pinning down is whether that old gravel loop was ever permitted. I looked at a property last year where a previous owner had graded a loop and run a water line without a permit, and the county's position was that the work had to be removed or brought up to current standard before anything new was approved. Quarry, ask planning to pull the file on your parcel and see what permits exist historically. If the loop is documented as part of an approved plan that was never finished, you may be in a much better position than starting fresh, and that is worth knowing before your attorney starts billing hours.